Figure 6.

JNK is involved in parkin mediated p21 degradation. A, Expression of pJNK in neural stem cells of non-tg or PARK2 KO mice. B, Neural stem cells were transfected with parkin shRNA, and then treated with JNK inhibitor, SP600125 (0, 5, 10 μM) and then checked the p21 expression by western blotting. C, Neural stem cells were cotransfected with constructs as indicated. At 48 hours after transfection, cells were treated with SP600125 (10 μM) and MG132 (10 μM) for 6hr, then harvested and immunoprecipitated with anti-p21. Ubiquitinated p21 was visualized by Western blot analysis using anti-ubiquitin. D, Neural stem cells were transfected with parkin shRNA, and then treated with JNK inhibitor, SP600125 (0, 5, 10 μM) and then differentiated into astrocyte or neuronal cells. E, Striatal pJNK levels are elevated after MPTP treatment for the induction of parkinson's disease. Immunoblot and quantification indicate that pJNK and p21 expression was increased in MPTP-treated mouse striatum compared with vehicle-treated controls. Each band is representative for three experiments. The data are expressed as the mean ± SD of three experiments. *P < 0.05 indicates significant difference from control shRNA treated groups. ^#P < 0.05 indicates significant difference from control of parkin shRNA treated groups.